William l



(No Model.)

W. L. MITCHELL.

GRATE. A No. 439,968. Patented Nov. 4, 1890.

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IVILLIAM L. MITCHELL, OF NEW YORK, N. Y.

G RAT E.

SPECIFICATION forming part of Letters Patent No. 439,968, dated November 4, 1890.

Application filed February 1, 1890. Serial No. 338,887. (No model.)

T0 00% whom it may concern.-

Be it known that I, WILLIAM L. MITCHELL, of New York city, in the county and State of New York, have invented a new and useful Improvement in Grates, of which the following is a full, clear, and exact description.

My invention relates to an improvement in grates for stoves, ranges, &c., and has for its object to provide a grate the basket or firesurface of which will be capable of a downward, backward, upward, and forward motion, and to so construct the basket that each alternate bar when in motion will move to the front, the remaining bars moving to the rear.

Another object of the invention is to so form each bar that a maximum of movement Q in the direction above indicated will be obtained when the crank-shaft connected with said bars is manipulated, and, further, to provide each bar with one or more spurs upon its upper face, whereby'the bed of coal supported by the grate may be agitated in an effective manner.

The invention consists in the novel construction and combination of the several parts, as Will be hereinafter fully set forth, and pointed out in the claims.

Reference is to be had to the accompanying drawings, forming a part of this specification, in which similar letters and figures of reference indicate corresponding parts in all the views.

Figure 1 is a plan view of a grate constructed in accordance with my invention, a portion thereof being broken away. Fig. 2 is an end View of the grate. Fig. 3is a transverse section on linen: a: of Fig. 1, and Fig. 4 is a bottom plan view of one of the grate-bars dctached from its frame.

In carrying out the invention the frame of the grate consists of a front bar 10, having formed integral therewith or attached thereto end bars 11. In the front bar 10 a series of horizontal, preferably rectangular, openings 12 is produced, the number of these openings being made to correspond with the number of bars employed.

At the rear of the end bars 11 of the grateframe, upon the under face of each of said bars, a bearing-box 13 is preferably formed, in which bearing-boxes a crank-shaft A is journaled, the said crank-shaftbeing provided jwith a series of crank-arms 14, which arms are arranged to extend in the same plane alternately horizontally outward from opposite sides of the shaft. One end of the crank-shaft ,is carried through the end bar, and the projectin g end is squared or made polygonal, as illustrated at 15 in Fig. 1, to receive any form of crank whereby the shaft may be rocked, and each end bar of the grate is provided with a trunnion 16, one of said trunnions being squared to receive a crank, the said crank being adapted for use in dumping the grate.

One of the crank-arms 14 of the crank-shaft is immediately opposite each of the openings 12 in thefront bar 10 of the frame.

convexed upon their under surfaces as shown at 18 in the same figure from a central point, the said concaved and convexed edges being continued to a point at or near each end. The forward extremity of each grate-bar is flat, being at a right angle to a vertical line drawn through the center of the bar, which flat portion 19 is adapted to enterand slide in one of the openings 12. At the rear end of each bar the upper edge is curved downward and rearward, and the said rear extremity is enlarged and provided with a vertical recess in the under face, the upper wall.

of which recess is circular, thus forming an essentially U-shaped or yoke-1ike extension 20. In the front and rear faces of the yoke like extensions of the bars a transverse groove or channel 2lis produced. Therecessed rear portion of each bar is made to fit over one of the crank-arms of the crank-shaft, and is held in position upon said crank-arm by passinga pin 22 from front to rear through the lower portion of-"the U-shaped-projection of the bars at the channeled surface thereof, and the ends of said pins are bent over in the channels, as best illustrated in Fig. 3, whereby the said pins are prevented from projecting and interfering with the movement of the grate-bars.

It will be understood that instead of journaling the crankshaft beneath the end bars of the frame it may be journaled in said bar on the top of the same, as in practice maybe found most advantageous or desirable.

The bars 13 of the grate are of peculiar formation, being concaved upon their upper surfaces as illustrated at 17 in Fig. 3, and

By reason of the construction above set forth when the crank-shaft is rocked each alternate bar will move to the front and the remainder to the rear with a downward and upward saw-like motion, thus greatly facilitating the agitation of the bed of coal upon it, and by reason of forming the concave upper surfaces 17 upon the grate-bars a central spur 26 is formed upon the upper surface of said bars, which also tends, by contacting with the coals, to increase the agitation of the latter as the bars are moved forward and backward, and, further, by concaving the upper surfaces of the bars at each side of the center a far greater bearing-surface is ob-'-' tained than if the bars were straight; and it will be observed by reference to Fig. 3 that in the operation of the bars so constructed the said bars act in opposition for a longer time in passing one another than if they were straight, the throw being the same as with a straight bar, but the results far superior.

Having thus described my invention, I claim as new, and desire to secure by Letters Patent 1. As an improved article of manufacture, a grate-bar provided with a spur upon its upper face, cavities at the sides of the spur, and a horizontal end, substantially as shown and described.

2. The combination, with a grate-frame the front bar of which is provided with a series of openings and a crank-shaft journaled at the rear of the frame, the crank-arms of which extend alternately in opposite directions, of grate-bars each provided with a spur upon its upper face and a cavity at each side of the spur, the rear ends of said bars being attached to the arms of the crank-shaft and the forward ends held to slide in the openings of the front bar of the grate, substantially as and for the purpose set forth.

3. The combination, with a grate-frame the front bar of which is provided with a series of openings and a crank-shaft journaled at the rear of the frame, the crank-arms whereof extend alternately in opposite directions, of a series of bars provided with a concaved surface at each side of the center, a central spur, and a straight forward end, the rear end of each of said bars being held in contact with one of the crank-arms of the crank-shaft, and the straightforward end being adapted to slide in one of the openings of the front bar of the frame, substantially as shown and described, and for the purpose specified.

4. The combination, with a frame the front bar whereof is provided with a series of openings and a crank-shaft journaled atthe rear of the frame, having one end projecting beyond the frame for the reception of a crank, the crank-arms of the shaft being alternately projected in opposite directions, of a series of bars concaved upon the upper face at each side of the center and provided with a central spur, a straight forward end, anda U-shaped extension or projection at the rear end, the U shaped projection of each bar being held in engagement with a crank-arm of the crankshaft, and the forward straight end being adapted to slide in one of the front bar-openings, substantially as shown and described.

5. Thecombination, with a frame provided with trunnions and having a series of openings produced in its front bar and a crankshaft journaled at the rear of the frame, provided with a series of crank-arms alternately projected in opposite directions, of a series of bars having their upper faces concaved at each side of the center and provided with a central spur, a flattened outerend adapted to move in the openings of the front bar of the frame, and a bifurcated or U-shaped rear end adapted for engagement with the crank-arms of the crank-shaft, the members of said U- shaped end being provided with channels in their outer faces near the bottom, and a pin passed through the channeled members of each U-shaped end of each grate-bar beneath the crank-arm with which it contacts, substantially as described.

WILLIAM L. MITCHELL.

Witnesses:

J. F. AOKER, J r., O. SEDGWICK. 

